A tornado siren

The sirens were a warning for all to hear, almost ear splitting, blaring from the outdoor warning system. There were tornado sightings in the area.

A Warning 

A warning symbol

It has been a watchful few weeks in the southern and plains area of the United States. It is tornado season in these regions, and tornado sirens are obligatory in the previously mentioned locations. The tornado sirens are extremely loud for one specific reason; to warn people of possible tornados. The noise must be loud enough in order for people to hear inside a building besides the great outdoors. Oxford Languages Dictionary defines the word Warning as “a statement or event that indicates a possible or impending danger, problem, or other unpleasant situation.” It is within these confines that I would like to issue a tea warning. National Geographic explains in everyday terms, a tornado can form when “warm humid air collides with cold, dry air.” There can be a tempest in the cup when green tea leaves combine with boiling water. 

How We Taste The Sensation Of Bitter

A steamed green tea in an earthen cup. Dry leaves are shown in a bamboo container, and wet leaves in an earthen gaiwan. 

On our tongues are located numerous taste buds, made up of five different types of cells. Type I through Type V taste bud cells each carry a different function. Type I, Type II, and Type III cells are what we use for the sensation of taste. Type IV and Type V taste bud cells are used for making new taste bud cells and for structurally supporting and aiding in the functioning of existing cells, respectively. There are five taste sensations; salty, sweet, bitter, umami, and sour. Type I through Type III taste buds are designed to specifically taste one of these five taste sensations. Basically, Type I taste bud cells pick up a salty taste. Type II taste bud cells are designed to register sweet, bitter and umami tastes. And a Type III cell can detect sour tastes. Once salty, bitter, sweet, sour, or umami is experienced by a specific taste bud, that taste bud sends a message to the nervous system, through the Type III cell, that it has experienced that taste. Taste bud types can have interactions among themselves that block a taste sensation, or analyze multiple taste sensations simultaneously. 

For example, while sipping tea, there are multiple flavors at once washing over the taste buds. It is the Type III taste bud cells that tell the brain all the other tastes in tea besides the sour taste. In tasting bitterness, it is the Type II cell that picks up that flavor. The Type I taste bud cells that pick up saltiness can also cancel the bitter signals that the Type II cell can pick up. When this occurs, the food or beverage will register as salty and not bitter because the cell cancelled the bitter signal that would have been sent to the nervous system via the Type III cell. Interestingly though, a Type II taste bud cell can cancel a sweet sensation or the sweet sensation can also cancel a bitter sensation. Confused yet? Suffice it to say, that taste buds are intricately designed mechanisms that each can pick up specific flavors. They can send or block tastes among each other and possibly send taste sensations directly to the nervous system.

The taste of bitterness can be mitigated by the number of taste bud receptors and combination of receptors that are sensitive to bitterness. There are at least twenty five different known varieties of bitter receptors in a person. These bitter receptors have different shapes. It is a bit like running a statistical analysis with the varied shapes and receptor numbers. Combined, the shapes of the receptors and the number of receptors can identify a myriad of bitter tasting chemicals. Other mitigating factors can include if someone has less Type II taste buds, or a different combination of taste bud shapes, they may not taste the sensation of bitter as well as another person. When an illness, or medicinal treatments affects the taste buds, or the signaling to the nervous system, food and beverages can have an altered taste. Food can have an enhanced bitterness, or the sensation of bitterness can be blocked all together.

Bitter Chemical Reactions Or A Green Warning

A green tea in a double-wall glass cup, with bubbles at the top of the tea

Aside from a medical reason a person’s taste sensation of bitterness might be affected, there are several external culprits that can affect the bitterness in green tea. Mold or foreign matter that has spoiled the tea could create a bitter taste in the cup. Also what was eaten prior to sipping tea could affect the sensation of bitterness in the cup. Other reasons tea could be bitter include incorrect storage of tea, calcium or magnesium in the water supply, antioxidants, tannins or caffeine molecules found in processed tea leaves. One easily controllable factor that greatly affects the bitterness in the cup is the temperature of the water used to steep the tea.

In steeping green tea in particular, caution and watch worthiness ideally needs to abound. Green tea can quickly become bitter during the steeping process. The culprits for the bitterness in green tea are catechins, caffeine and two specific flavonol chemical compounds, kaempferol and quercetin, found in the Camellia sinensis tea leaf. Of the two chemicals, it is quercetin that is more water soluble and can leach into the tea water more readily, giving off a bitter taste. The hotter the water, the more quercetin that could potentially be leaked from the tea leaf into the water.

Caffeine can additionally give off a bitter taste in a cup of tea. Green tea has not been oxidized, therefore has little to none of the chemical theaflavin. In teas that have been oxidized, theaflavins bind to the caffeine molecule and tempers the bitter taste of the caffeine molecule. This action does not occur in green teas because of a lack of theaflavins. Thus, the caffeine molecules are unrestricted in their movement, causing the bitter taste in the cup. Plus, caffeine can be extracted from the tea leaf at a faster rate with hotter water than colder water.

Lastly, catechins (antioxidants) are the main culprits for bitter green tea. They are bitter tasting antioxidants that have not been broken down in the oxidation stage of other teas. The lack of oxidation and the quick denaturing, or killing the green, stage in green tea processing, aids in keeping the leaf from further chemical changes. This lack of chemical changes keeps the antioxidants intact. Catechins are extremely water soluble the hotter the water used for steeping tea. Boiling water used for green tea is a recipe for disaster. The boiling water has a rapid fire effect of pulling out, or leaching out, all the bitter tasting catechins. The result is a bitter tasting green tea.

How To Fix A Bitter Taste

There is a saying that states “An ounce of prevention is worth a pound of cure.” Related to tea, this means watch, monitor, or control the water temperature for steeping green tea. There are numerous tea steeping guidelines for appropriate temperatures for each category of tea. The main takeaway is keeping the water temperature under 175 degrees F for steeping green tea. Personally, I find anything over 175 degrees F too hot for steeping green tea, and I am left with a bitter cup of tea.

The amount of tea leaves and the length of steeping green tea does affect the bitterness in the tea. The longer the steep time, the more catechins can be pulled out of the tea leaves and into the cup. In addition, a larger amount of leaves used for steeping tea will increase the amount of catechins that are leached into the teacup, regardless of steeping time.

Several helpful hints besides controlling water temperature, steep time and amount of tea being steeped is to have on hand salt and sugar. As previously discussed, salt and sugar can cancel out the Type II taste buds registering the bitterness in the tea. A scant amount of salt or sugar will block the bitterness in the cup of tea. 

A bitter tasting cup of tea can be fixed. But in my mind, it is more efficient to heed the warnings about steep time, amount of tea leaves, and water temperature for steeping tea. A cup of green tea doesn’t have to be bitter, just mind the warnings.

Watchfully steeping my green tea, yet, still learning as I steep,



Lovelace, Virginia Utermohlen.Tea: A Nerd’s Eye View.VU Books, 2020.

About The Author

A photo of Leslie on the patio wearing a pink cardiganLeslie Sundberg is a World Tea Academy Certified Tea Specialist, a World Tea Academy Apprentice Tea Sommelier, a Specialty Tea Institute Level IV trained Tea Specialist, and a Tea and Business Etiquette Specialist. On any given day, Leslie can be found teaching, speaking or sharing in the joys of a cup of tea.  No matter what Leslie is doing or where she is, one thing remains constant: 4:00 in the afternoon is tea time!

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